Photosynthesis assembling of ZCS/PO/Ni3Pi2 catalyst for three-stage photocatalytic water splitting into H2 and H2O2

Abstract

Photocatalytic intermediate water splitting (PIWS) provides a promising route for hydrogen production as its high product value, favorable kinetics and easy separation. However, the traditional oxide and sulfide-based catalysts either respond to ultraviolet light or suffer from severe photocorrosion and sluggish kinetics, leading to poor conversion efficiency. Herein, we employ a two-step photosynthesis strategy to prepare an inexpensive phosphorus (PO) protection layer and nickel phosphate (Ni3Pi2) cocatalyst on the Zn0.14Cd0.86S (ZCS) photocatalyst, which shows a H2 and H2O2 evolution rate of 1.464 and 1.375 mmol h−1 g−1 in water splitting under 20 h visible light irradiation. The excellent PIWS performance originates from a combination of anti-photocorrosion ability of PO protection layer and bi-functional role of Ni3Pi2, which decompose into Ni2P and NiPi to enhance the H2 and H2O2 evolution. Moreover, the two-step photosynthesis process triggers photocatalytic partial water splitting (PPWS) by oxidizing NaH2PO2, with H2 evolution rate of 9.26 and 9.53 mmol h−1 g−1, respectively. This work develops a photosynthesis assembling of ZCS/PO/Ni3Pi2 catalyst, which not only presents superior performance for H2O2 evolution but also achieves a high average H2 production rate of 0.28 mmol h−1 under 25 h visible light irradiation by integrating the three-stage PPWS→PPWS→PIWS process.